Polypropylene resin compositions are materials excellent in rigidity, impact resistance, etc, and they, therefore, are used in a wide variety of applications in the form of molded articles such as automotive interior or exterior components and housings of electric appliances. It is known that polypropylene resins are used with incorporation of a heat resistance stabilizer, a weathering stabilizer or an antistatic agent according to the performance demanded in the intended application.
On the other hand, a polypropylene resin composition containing such additives may result in occurrence of defective appearance with a product due to accumulation of volatile components on the surface of a mold during its molding process such as injection molding carried out continuously by the use of the mold. In order to cope with such staining of molds, improvement by addition of a specific additive has been made.
For example, Japanese Unexamined Patent Application Publication No. 2002-12720 discloses a polypropylene resin composition containing 0.0 to 0.5% by weight of three kinds of hindered amine light stabilizers each having a specified structure and a specified molecular weight and 0.01 to 0.5 parts by weight of a triarylphosphite type heat resistance stabilizer.
Japanese Unexamined Patent Application Publication No. 10-292072 discloses a polypropylene resin composition comprising 0.01 to 0.2 parts by weight of a hindered phenol antioxidant, 0.01 to 0.3 parts by weight of a weathering agent, 0.01 to 0.2 parts by weight of a fatty acid amide and/or a fatty acid bisamide, and 0.01 to 2.0 parts by weight of an antistatic agent.
Polypropylene resin compositions, however, have been required to be better balanced with respect to antistatic property, weather resistance, and anti-mold staining property at the time of their molding.